The invention relates to a tensioning device for a traction-mechanism drive, in particular, for a belt drive that is integrated as such in an internal combustion engine, in order to drive components of the engine or installed accessories, such as, for example, injection pumps, power steering pumps, generators, water pumps, air-conditioning compressors, or comparable units.
From WO 2007/113039, a belt-tensioning device is known that has a cup-shaped housing and a swivel arm supported thereon so that it can pivot. This belt-tensioning device further comprises a torsion spring that is constructed as a cylindrical spring and by which a torque that acts between the cup-shaped housing and the swivel arm is generated. Using this torque it is possible to force a tensioning roller attached to the swivel arm against a belt section, typically a loose belt section of the belt drive and, in this way, to create a sufficient tensioning function for maintaining the friction-fit coupling of the disks of the belt drive. Furthermore, between the cup-shaped housing and the swivel arm, a friction ring structure is active through which the movement of the swivel arm can be braked by Coulomb friction, through which belt oscillations are damped.
From DE 101 31 916 A1, a tensioning device for traction mechanisms is similarly known, in particular, a belt-tensioning device. This tensioning device similarly comprises a fastening structure and a swivel arm that is supported thereon so that it can move and that is provided with a tensioning roller. The pivoting motion between the swivel arm and the base structure is damped by a bushing element that is inserted into the inner region of a helical spring acting as a restoring spring and that provides, as such, friction contact surfaces.
From EP 0 967 412 A2, DE 100 63 638 A1, EP 0 866 240 B1, EP 0 450 620 B1, and DE 10 2004 047 422 A1, additional belt tensioning devices are known that each have a spring-loaded swivel arm whose pivoting motion is damped by braking devices.
Furthermore, from WO 02/068841, a tensioning device is known that comprises a swivel arm that is similar to the tensioning devices noted above and that is supported on a bearing journal so that it can pivot. Attached to the bearing journal structure is a cover element that comprises a plate-like element and a friction disk and that sits on one end of the swivel arm surrounding the bearing journal.